Throughout his career Garnaut held a number of influential political and economic positions as: senior economic adviser to Prime Minister Bob Hawke (1983–85), Australia's ambassador to China (1985–88), chairman of the Primary Industry Bank of Australia (1989–94), chairman of BankWest (1988–95), head of division in the Papua New Guinea Department of Finance (1975–76) and chairman of Lihir Gold.

On 30 April 2007 the state and territory governments of Australia, at the request of Kevin Rudd, then leader of the Australian Labor Party and Leader of the Opposition, appointed Garnaut to examine the impacts of climate change on the Australian economy and recommend medium to long-term policies and policy frameworks to improve the prospects for sustainable prosperity.[5] The Garnaut Climate Change Review was finalised on 30 September 2008,[6] with a finalised update being released on 31 May 2011.[7] Garnaut concluded his role as climate change advisor for the Australian Government on 30 June 2011.[8]

The final report was released on 30 September 2008[16] and recommended that Australia should indicate at an early date its preparedness to play its full, proportionate part in an effective global agreement that ‘adds up’ to either a 450 or a 550 emissions concentrations scenario, or to a corresponding point between.
Australia’s full part for 2020 in a 450 scenario would be a reduction of 25 per cent in emissions entitlements from 2000 levels. For 2050, reductions would be 90 per cent from 2000 levels (95 per cent per capita). Australia’s full part for 2020 in a 550 scenario would be a reduction in entitlements of 10 per cent from 2000 levels. For 2050, reductions would be 80 per cent from 2000 levels or 90 per cent per capita. If there is no comprehensive global agreement at Copenhagen in 2009, Australia, in the context of an agreement among developed countries only, should commit to reduce its emissions by 5 per cent (25 per cent per capita) from 2000 levels by 2020, or 13 per cent from the Kyoto compliance 2008–12 period.[17]

The report's recommendations in terms of policy, apart from a Carbon Pollution Reduction Scheme which included forestry and agriculture, centred heavily on hoping that carbon capture and storage and other coal pollution mitigation technologies would be available on a wide scale within the next twenty years.

Responses from political parties were mixed. Australian Greens leader Bob Brown showed that the report demonstrated that reducing greenhouse gas emissions would not come at the expense of Australia's economic growth.[23] Climate Change Minister Penny Wong did not comment directly on the report but said that economic responsibility needed to be considered in responding to the report, and that the Government would wait before Treasury modelling on climate change mitigation before responding.[24]

In November 2010 the Minister for Climate Change and Energy Efficiency commissioned Professor Garnaut to update his 2008 Garnaut Climate Change Review.[25] Eight papers were released in February and March 2011[26] and the final report of the Garnaut Climate Change Review Update 2011 was presented to the Government on 31 May 2011.[7]

In September 2010, Professor Garnaut was appointed as an independent expert advisor to the Multi-Party Climate Change Committee.[27] The committee will explore options for the implementation of a carbon price and will help to build consensus on how Australia will tackle the challenge of climate change.

Ross Garnaut commented after Cyclone Yasi affected Queensland in 2011 that the extensive body of climate science suggested that "cyclonic events will be more intense in a hotter world". He further noted that if there were an intensification of extreme weather events with less than one degree of warming experienced and, if strong emissions growth was expected from many rapidly growing developing countries, then "you ain’t seen nothing yet" in terms of the intensification of extreme weather events.[28][29][30] Recent studies by Australian scientists have detected a long-term shift towards wet extremes and hot extremes occurring at the same time, consistent with changes as a result of increased concentrations in greenhouse gases.[31][32]

On 23 June 2015, Garnaut is scheduled to deliver the annual Luxton Memorial Lecture at the University of Adelaide in South Australia. His talk is entitled Australia: Energy superpower of the low carbon world.[33]

In 2008, Garnaut was of the opinion that nuclear was not obviously necessary in Australia's low carbon energy future. He told the media:

"Nuclear energy is an important part of the global response to a low-carbon economy, but under Australian circumstances, it is not obvious that nuclear is an important part of our answer."[34]

His position on the matter was countered by Ziggy Switkowski, leader of the 2006 UMPNER Review, and an advocate for nuclear power in Australia.

Garnaut considers nuclear power to be a "low emissions" energy source, given its negligible emissions of carbon dioxide to the atmosphere during plant operation. As such, he supports nuclear power as part of global efforts to reduce greenhouse gas emissions especially given rising energy consumption in Asia. He has also publicly noted China's commitment to expanding its fleet of nuclear reactors, even in the wake of the Fukushima disaster.[35][36]

2009 (with Ligang Song and Wing Thye Woo (eds), China’s New Place in a World in Crisis. Australian National University E-Press (Canberra), Brookings Institution Press (Washington) and Social Sciences Academic Press (China).

2003 (with Ligang Song, (eds.), China: New Engine of World Growth. Asia Pacific Press, The Australian National University Press, Canberra.

2003 (with Rana Ganguly and Jongsoon Kang), Report to the Department of Immigration and Multicultural and Indigenous Affairs, Migration to Australia and Comparisons with the United States: Who Benefits? Commonwealth of Australia, Canberra.